Chlorine-containing polymers [e.g. polyvinyl chloride (PVC), polyvinylidene chloride (PVDC)]and aromatic polymers (e.g. polyesters, polycarbonates, polystyrenes, polyphenylene oxides) are widely used in applications such as food containers, packaging materials, daily sundries, automotive interior trim parts, building materials, industrial materials and the like.
In some of these applications which require such properties as chemicals resistance, water resistance, hot-water resistance and gas barrier property, lamination of said chlorine-containing polymer or said aromatic polymer and a polyolefin (e.g. polyethylene, polypropylene) has been tried in order to allow the chlorine-containing polymer or the aromatic polymer to have said properties. However, no adhesive having excellent adhesion characteristics at high temperature has been developed yet. For instance, when an epoxy groupcontaining polyolefin known as a conventional adhesive polyolefin is used as an adhesive for lamination of a polyolefin and an aromatic polymer, no excellent adhesion characteristics can be obtained. Further, in direct lamination of an aromatic polymer and said modified polyolefin, no excellent adhesion characteristics can be obtained, either.
On the other hand, it is well known to use chlorinated polyethylene as an adhesive for adhered polymers mentioned above.
Japanese Patent Publication No. 18891/62 discloses a method wherein in bonding a film or sheet of a halogenated vinyl or vinylidene polymer to a polyolefin film or sheet, the back side of the polyolefin film or sheet is halogenated and the two films or sheets are directly melt-bonded.
Japanese Patent Publication No. 27236/70 discloses a method wherein a chlorinated ethylene polymer having a chlorine content of 33 to 55% by weight, an oxygen content of 0 to 3.0% by weight, a crystallinity of 1% or lower and an inherent viscosity of 0.2 to 1.8 is used as an adhesive for plasticized vinyl chloride polymers.
Japanese Patent Publication No. 47292/72 discloses a hot-melt adhesive consisting of 100 parts by weight of essentially amorphous chlorinated polyethylene containing 30 to 65% by weight of chlorine and obtained by chlorinating high density polyethylene at a temperature of 100.degree. C. or higher, and 0.5 to 5 parts by weight of an organic peroxide.
Japanese Patent Publication No. 41677/76 (corresponding to U.S. Pat. Nos. 3532795 and 3549389) describes a method wherein a polyolefin layer and a barrier layer, the main portion of which is composed of vinylidene chloride, are bonded with one of several adhesives including chlorinated polyethylene to produce a packaging film.
Japanese Laid-Open Patent Publication No. 81379/81 proposes chlorinated polyethylene having a chlorine content of 10 to 50% by weight and a polymer composition composed mainly of said chlorinated polyethylene, for use as an adhesive for bonding of a polyvinyl chloride mixture and a polyethylene.
Japanese Patent Publication No. 1710/83 discloses a resin composition comprising 100 parts by weight of a carboxyl-modified ethylene/vinyl acetate copolymer and 10 to 300 parts by weight of chlorinated polyethylene, for use as an adhesive for bonding a polyester resin to itself or to an other substrate.
Thus, the above prior art references describe that chlorinated polyethylene can be used as an adhesive singly or in combination with an other component. The chlorinated polyethylenes used in the prior art contain chlorine in an amount of at least 10% and, in some cases, as high as 60% in order to reduce the crystallinity of polyethylene and to impart adhesive property to the polyethylene. For instance, in Japanese Laid-Open Patent Publication No. 81379/81 mentioned above, there is used, as an adhesive, a chlorinated polyethylene obtained by chlorinating polyethylene to chlorine contents of 10 to 60% by weight. However, chlorine contents of 10 to 20% by weight can not provide sufficient adhesion strength. In contrast, chlorine contents above 20% by weight can not provide sufficient adhesion characteristics at high temperature even if it can provide sufficient adhesion characteristics at normal temperature.
Japanese Patent Publication No. 35091/75 discloses a coating composition for a molded article of polypropylene, which contains, as a main active component, a chlorinated, amorphous propylene/ethylene copolymer obtained by chlorinating an amorphous propylene/ethylene copolymer having an ethylene content of 2 to 30% by weight (about 3.1 to 39 mole%), being substantially free from any solvent and having an [.eta.]of 0.3 to 1.5, to a chlorine content of 5 to 35%. This chlorinated propylene/ethylene copolymer includes those having a relatively low chlorine content but requires, in its production, the use of an amorphous propylene/ethylene copolymer as a starting material.
Such a chlorinated, amorphous propylene/ethylene copolymer has insufficient adhesion characteristics at high temperature.
Japanese Patent Publication No. 37688/75 discloses an adhesive for molded articles of polyolefin, which is mainly composed of a chlorinated propylene/ethylene copolymer obtained by chlorinating a propylene/ethylene copolymer having an ethylene content of 2 to 15% by weight (about 3.1 to 21.0 mole%). It is described in the publication that the chlorinated propylene/ethylene copolymer has a chlorination degree of 20 to 40% by weight, preferably 22 to 35% by weight. Further, it is taught in the publication that, when the chlorination degree is lower than said range, the chlorinated propylene/ethylene copolymer has poor workability and, upon being left standing, gels and becomes unusable as it is and, when the chlorination degree is high than said range, the chlorinated propylene/ethylene copolymer has reduced adhesion strength and therefore is practically valueless as an adhesive.
In said Japanese Patent Publiction No. 37688/75, the chlorinated propylene/ethylene copolymer is dissolved in a solvent such as toluene and the resulting solution is used as a heat-sealing agent for polyolefin films. The publication makes no mention of whether or not the chlorinated propylene/ethylene copolymer has adhesion to chlorine-containing polymers or aromatic polymers, or of the crystallinity and molecular weight distribution of the copolymer used as a starting material in the chlorination reaction. Thus, the chlorinated propylene/ethylene copolymer of Japanese Patent Publication No. 37688/75 is characterized by its excellent workability (uniform dissolution in solvents) as compared with chlorinated isotactic polypropylenes, in spite of its low chlorine content. From this matter, it is apparent that the propylene/ethylene copolymer used in the invention of Japanese Patent Publication No. 37688/75 is an amorphous propylene/ethylene copolymer. As mentioned previously, the chlorination product of such an amorphous propylene/ethylene copolymer is inferior in heat resist- ance.
Japanese Laid-Open Patent Publication No. 133081/85 (corresponding to European Patent Application No. 149356) discloses an adhesive for chlorine-containing polymers or aromatic polymers, which is a chlorination product of a polyolefin (A) having a crystallinity of 50% or below and has a chlorine content of 0.1 to 10% by weight.
Japanese Laid-Open Patent Publication No. 8643/72 (corresponding to UK Patent No. 1373805) describes an invention relating to a halogenation process for polyolefins. It is disclosed in Example 2 that a propylene/butene copolymer having a Y-Red-value of 0.47 and a melt viscosity of 43,000 cp at 190.degree. C. and containing less than 0.1% of heptane-insoluble component was dissolved in CCL.sub.4 and chlorinated with chlorine gas to obtain a polymer having a chlorine content of 67.0%.
Japanese Patent Publication No. 33663/75 (corresponding to UK Patent No. 1285836) discloses an invention relating to an electrophotographic element obtained by coating an electroconductive substrate with a photoconductive composition consisting of a nonpolymeric organic photoconductive substance and a halogenated poly(.alpha.-olefin) binder. Example 8 uses, as the binder, a chlorinated propylene/butylene copolymer (propylene: 50%) having a chlorine content of about 60% by weight.
Hence, an object of the present invention is to provide a novel chlorinated polyolefin.
Another object of the present invention is to provide an adhesive containing the chlorinated polyolefin of the present invention as an adhesive component.
Still another object of the present invention is to provide an adhesive which exhibits excellent adhesion characteristics for chlorine-containing polymers or aromatic polymers even in high temperature atmospheres.
A further object of the present invention is to provide a laminate of a chlorine-containing polymer or an aromatic polymer bonded with the adhesive of the present invention.
Other objects and advantages of the present invention will become apparent from the following de- scription.